Siren announces a new plan to Mephisto, who gives her more evil noise. She appears before Hummy, claiming to have been kicked out by Mephisto, to which Hummy decides to help hide her, keeping it a secret from Hibiki and Kanade. Siren pretends to change sides, claiming she wants to sing the Melody of Happiness with Hummy, requiring a set of Notes and all the Fairy Tones. When Hibiki and Kanade confront Hummy after hearing about the situation from Ako and Souta, Hummy remains defiant that Siren can be trusted. Hummy and Siren run into the Minor Trio, who turn all the Notes Siren was carrying into a powerful Jar Negatone. As the PreCure struggle against the Negatone, Siren has the Notes inside it fight against each other to give the PreCure an opening to defeat it. Siren then reveals her true intentions, stealing the Fairy Tones and the Notes inside them and delivers them to Mephisto.
ハミィがご機嫌だった。しかし、その理由は教えてくれない。気になった響たちは、理由を探ろうとする。すると、奏太たちから、黒いネコと一緒にいたハミィを見かけたという情報を入手するが...。
